Reversible pump



Aprifl w, 1945. E, s. WITCHGER REVERSIBLE PUMP Filed April 7, 1944ROT/IT/aw INVENTOR. [age 7e 5 1% ZM er: BY A. fivZQ Patented Apr. 10,1945 REVERSIBLE PUMP Eugene S. Witchger, Grosse Pointe Woods, Mich,assignor to Eaton Manufacturing Company, Cleveland, Ohio, acorporationof Ohio Application April 7, 1944, Serial No. 530,014

3 Claims.

This invention relates to pumps and particularly to pumps of the rotarytype having cooperating internal and external rotors, the principalobject being the provision of a pump of this type that is automaticallyreversible so that regardless of the direction of rotation itcontinually pumps in the same direction.

Objects of the invention include the provision of an automaticallyreversible pump; the provision of a rotary pump which will continuouslypump in the same direction regardless of the direction of rotationthereof; the provision of a pump having pumping means comprising a pairof rotors one within and eccentric to the other and havin interengagingteeth forming pumping chambers between them, inlet and outlet portscommunicating with such pumping chamber, and the outer of the rotorsbeing so shiftable in the direction of its plane of rotation between twodifierent limiting positions that the expanding pumping chambers formedbetween the teeth of the rotors remain continuously in opencommunication with the inlet port and the contracting pumping chambersformed between the teeth of the rotors remain continuously in opencommunication with operation, and economical to manufacture.

The above being among the objects of the present invention the sameconsists in certain novel details of construction and combinations ofparts to be hereinafter described with reference to the accompanyingdrawing, and then claimed, having the above and other objects in view.

In the accompanying drawing which illustrates a suitable embodiment ofthe present invention and in which like numerals refer to like partsthroughout the several difierent views,

Fig. 1 is a vertical sectional view, taken axially through a pumpconstructed in accordance with the present invention, as on the line l-lof Fig. 2;

Fig. 2 is a transverse sectional view taken on the line 2-2 of Fig. 1and showing the rotors in end view, with the rotors in the relativepositions which they assume when turningin a clockwise direction ofrotation;

Fig. 3 is a view similar to Fig. 2, but with the rotors removed from thehousing, showing the inlet and outlet ports; and,

Fig. 4 is a view similar to that in Fig. 2, but showing the rotors inthe relative positions which they assume when rotating in acounterclockwise direction of rotation.

The pump of the present invention employs cooperating rotor elementsconforming generally to those disclosed in United States Letters PatentNos. 1,682,564, dated August 28, 1928, and particularly United StatesReissue Patent No. 21,316. dated January 9, 1940, both to Myron F. Hill,or to any mechanically equivalent structure. In other words, it hasparticular relation to that type pump including a pair of toothedrotors, one Within and eccentric to the other and having at least oneless tooth division than the other, the teeth having diametricallyopposed i'ull mesh and open mesh positions and prererabiy remaining insub stantially contacting relationship with respect to each otherbetween such positions. One rotor is driven, thus driving the other ofthe rotors through the inter-engagement of their respective teeth and asthe interengaging teeth move away irom the full mesh position in thedirection of rotation they open between them pumping chambers winchcontinue to increase in volume to open mesh position and which chambersdecrease in volume from open mesh position to full mesh po-- sition inthe direction of rotation. In the drawing, the inner rotor is indicatedat Ill and the outer rotor at H, the inner rotor being shown as havingfour teeth It and the outer rotor as having five teeth 15.

It has been conventional practice to provide such rotors in a pumpstructure and each for rotation about a fixed axis, the pump housingbeing provided with an inlet port communicating with those pumpingchambers increasing in volume and an outlet port communicating withthose pumping chambers decreasing in volume. Because of the fact eachsuch rotors has each been mounted for rotation about a fixed axis, itwill be appreciated that if the direction of rotation of the pump isreversed the pumping chambers of increasing volume are shifted from oneside of a medial plane including the full mesh and open mesh positionsto the opposite side thereof and consequently the direction of flow offluid through the pump is correspondingly reversed. In accordance withthe present invention, instead of mounting the (outer rotor for rotationabout a fixed axis as only, while the pumping chambers of decreasingvolume remain in open communication-with the other of the ports only.The bodily shiftable position of the outer rotor is automaticallycontrolled by the direction of rotation of the rotors, the pumping forceset up between them automatically eifecting the required movement of theouter rotor. Thus, the pump will operate to pump continuously in onedirection regardless of its directlon of rotation, this being extremelyimportant in many installations as will be readily appreciated by thoseskilled in the art.

The actual form of the pump embodyini the present invention may, ofcourse, vary widely, the form shown in the drawing for the P rpose ofi1- lustration being of an extremely simple type for ease indescription. As shown, it comprises a cast body indicated generally at28 having a pumping chamber indicated generally at 22 opening onto oneend face thereof, which face is normally closed by a cover or cap member28 secured thereto by means of screws 28. A shaft 28 is rotatablysupportedin the housing 28 and projects through the pumping chamber 22,its outer or righthand end, as viewed in Fig. 1, hearing in a suitablebore 38 provided concentrically therewith in the cover or cap member 24.The inner rotor i is received on the shaft 28 within the pumping chamber22 and is secured thereto for equal rotation as by means of a key 32.The rotor 10 is preferably of substantially the same axial length as thedistance between the inner wall of the cap member 24 and the bottom ofthe pumping chamber 22, only that amount of axial clearance beingpreferably provided for the rotor which is necessary for a running fit.If desired, relative axial movement between the drive shaft 28 and theinner rotor l0 may be prevented by means of snap rings 34, one snappedinto each of co-operating circumferential grooves formed in the shaft,28 at each end of the rotor Ill.

The rotor l2 surrounds the rotor ID in the chamber 22 in the relationdescribed and cooperates with the inner face of the cap member 24 andthe bottom wall of the pumping chamber 22 in the same manner as therotor l0. Although, in the broader aspects of the invention, the rotorl2 may be provided with a surrounding hearing or other member, in theconstruction shown and by way of simplicity, the bearing for the rotori2 is provided by direct contact with periphcral wall portions of thepumping chamber 22, the pumping chamber 22 being of materially largersize than the outer rotor l2 so that the latter may shift bodily thereinin the plane of its rotation.

In order tolimit the bodily shiftable movement of the outer rotor I2,the peripheral wall of the pumping chamber 22 is formed to provide'threedistinct areas, one extending from a point indicated at A to a pointsuch as indicated at B, another extending from the point A in theopposite direction to a point indicated at C, and the third constitutingthe remainder of the peripheral walls of the chamber 22 and extendingfrom B to C, the latter being generally disposed at a greater distancefrom the axis of the shaft 28 than the first two surfaces so as toprovide ample clearance in the chamber 22 for the shifting of the outerrotor I 2,

The surfaces A-B and A-C are substantially quarter circular in plan viewas shown in Figs. 2, 3, and 4 and each is of a radius equal to theradius of the peripheral surface of the outer rotor I2. The center ofcurvature for the surface AB is indicated at D, best shown in Fig. 3,and the center of curvature for the surface A-C is indicated at E, thesecenters D and E being equally disposed on diametrically opposite sidesof the center of rotation of the inner rotor l0 which,

as indicated, is the axis F of the shaft 28. The

distance between the center F and each of the centers D and E is equalto the eccentricity of the rotors l8 and I2 so that when the outer rotor12 is lying in contact with the surface A-C, as viewed in Fig. 2, or incontact with the surface A-B, as shown in Fig, 4, it is rotatablysupported in the proper eccentric relation with respect to the innerrotor III in both cases. The surfaces A-B and A0 not only serve ashearing surfaces for the outer rotor l2, but also serve as stop surfaceswhich limit bodily shiftable movement of the outer rotor l2 in eitherone direction or the other in the plane of its rotation in the chamber22 as will be readily appreciated.

It -will be understood that in a pump having pumping elements of thetype described the positions of full mesh and open mesh of the teeth ofthe pumping element will be in a plane including the axis of rotation ofthe inner rotor and the axis of rotation of the outer rotor. In theconstruction shown and as viewed in the drawing this plane is ahorizontal plane perpendicular to the plane of the paper including thepoint F on, and the axis of the shaft 28, and including the points D andE. Consequently when the outer rotor 12 is in the position shown in Fig.2 where its axis of rotation is the point E, the point of full meshbetween the teeth of the rotors will be at the lefthand side of the pumpin horizontal alignment with the axis of the shaft 28 and the positionof open mesh will be at a diametrically opposite point on the righthandside of the shaft 28. Conversely when the rotors are in the positionillustrated in Fig. 4 the axis of rotation of the outer rotor I 2 willbe the point D under which conditions the above relation of parts willbe reversed, that is, the point of full mesh will lie on the righthandside of the shaft 28 in horizontal alignment with the axis of the shaft28 and the point of open mesh will lie diametrically opposite from theaxis of the shaft 28 therefrom.

The pumping action in a pump of the type described is obtained throughpumping chambers which are opened up, or increase in volume, as

the teeth move from full mesh position in the direction of rotation ofthe pumping element to open mesh position, and through, contraction orclosing of such pumping chambers as the teeth of the two rotors movefrom open mesh position in the dlrectionof rotation of the rotors tofull mesh position. Thus in the construction shown in the drawing wherethe outer rotor I2 is in the position indicated in Fig. 2 and the rotorsare turning in the direction of the arrow identifying such direction inthat figure, the fuli mesh position is at the left-hand side of thecenter F of the shaft 28 and in horizontal alignment therewith and thepumping chambers formed between the teeth II and I 6 of the rotors l8and i2 and increasing in volume lie above the axis of the the outerrotor I2 is in the position indicated in Fig. 4 the point of full meshis in horizontal ali n ment with the axis F of the shaft 28 but to theright of the axis F of the shaft 28 while the open mesh position is onthe diametrically opposite side of the shaft 28. However,'it will'beappreciated that in this last case and when the rotors l and 12 areturning in the direction of the arrow shown in Fig. 4 identifying thedirection of rotation and which is opposite to that shown in Fig. 2, theexpanding chambers formed between the teeth of the rotor still lie abovethe axis at the shaft 28 while the contracting chambers formed betweenthe teeth still lie below the axis F of the shaft 28. In other words,regardless of whether the relative positions of the rotors l0 and i2 arethat illustrated in Fig. 2 or that illustrated in Fig. 4, when therotors are turning in the respective directions illustrated in theseviews, the expanding pumping chambers formed between the teeth of therotors always lie above the axis of the shaft 28 and the contractingpumping chambers formed between ing chambers formed between the teeth ofthe rotor, and the similarly formed outlet port 42 formed in the innerface of the chamber 22 is always in open communication with thecontracting pumping chambers, regardless of whether the rotors are inthe position illustrated in Fig. 2 or in the position illustrated inFig. 4.

The outer rotor I2 is automatically shifted to the position illustratedin Fig. 2 when the pump is rotating in the direction illustrated in Fig.2 by the pressure built up between the teeth of the rotors cooperatingto form contracting pumping chambers, and likewise is automaticallyshifted to the position illustrated in Fig. 4 for the same reasonwhenever the direction of rotation of the pump is reversed from thatindicated in Fig. 2. Thus, the outer rotor I2 is shifted between itslimits of shiftable position indicated in Figs. 2 and 4 automaticallywhenever the direction of rotation of the pump is reversed and inaccordance with the direction of rotation of the pump. It will beappreciated that the outer rotor i2 in shifting in the manner describedfrom aposition of the rotary type is provided in which the direcin whichits axis of rotation is on one side of the 1 axis of the shaft 28 to aposition in which'its axis is on the diametrically opposite side. ineflect isv bodily shifted, or rotated, about the axis of the shaft 28through an angle of 180, The extent a of such angularity is not criticalas it will be appreciated that any angularity suflicient to reverse theeffective relation of the ports with respect to the points of full meshand open mesh of the rotors will ordinarily suflice.

The expanding chambers formed between the cooperating teeth of thepumping elements form,

of course, chambers in which the fluid being an outlet port openingthereinto, and said surfaces tion of flow of fluid through the pumpremains constant regardless of the direction of rotation of the pump andthat this important feature is obtained in a simple and effective mannerand with:

out requiring the addition of any parts whatsoever as compared tosimilar types of pumps in which the direction of flow of fluid isreversed upon reversal of the-direction of rotationof the pump.

claim by Letters Patent is:

What I claim is:

1. In a pump structure, in combination, a housing having a pumpingchamber therein, a pair of rotors in said housing one within andeccentric to the other, said rotors having interengaging teeth havingdiametrically opposite full mesh and open mesh positions, means formounting and driving the inner of said rotors about an axis fixed withrespect to said housing, the outer of said rotors being bodily shiftablein said chamber in the plane of its rotation under the infiuence of thepumping force built up by said rotors between two difierent positionscorresponding with the direction of rotation of said inner rotor, saidchamber being of materiallygreater area viewed axially of said rotorsthan said outer rotor and being formed to provide stop surfaces forengagement with said outer rotor to limit said shiftable movementthereof to said two positions and to provide direct bearing surfacestherefor, said housing having an inlet and an outlet port opening intosaid chamber so constructed and arranged in relation to said shiftablepositions of said outer rotor that the pumping chambers formed betweensaid teeth lea -ling said full mesh position in the direction ofrotation of said rotors and approaching said open mesh position are incommunication with said inlet port, and the pumping chambers formedbetween said teeth leaving said open mesh position and approaching saidfull mesh position in the direction of rotation .of said rotors are incommunication with said outlet port, regardless of the direction ofrotation of said rotors.

2. In a pump structure, in combination, a housing having a pumpingchamber therein,

pumping means in said chamber comprising a pair of rotors one within andeccentric to the other, said rotors have interengaging teeth thereoncooperating to form pumping chambers and said teeth having diametricallyopposite full mesh and open mesh positions, the inner of said rotorsbeing rotatable about an axis fixed with respect to said housing, saidchamber being of materially greater area viewed axially of said rotorsthan said outer rotor and said outer rotor being bodily shiftable insaid chamber in the plane of its rotation, said chamber providing apairj of stop surfaces each independently cooperable with said outerrotor to limit such shiftable movement thereof and said outer rotorbeing unrestricted in its shiftable movement in said chamber exceptfllorits engagement with said inner rotor and said stop surfaces, saidhousing having an inlet port and being so constructed and arranged as tomaintain the pumping chambers opening up between said teeth moving awayfrom said full mesh position and approaching said open mesh position incom-,- munication with said inlet port, and the pumping chambers formedbetween said teeth moving away from said open mesh position and ap-Having thus described my invention, what I proaching said tull meshposition in open coinmunioation with said outlet port, regardless of thedirection of rotation of said rotors and the consequent correspondingshiitable position or said outer rotor.

3. In a pump structure, in combination, a housing having a pumpingchamber therein, pumping means in said chamber comprising a pair ofrotors one within and eccentric to the other, said rotors haveinterengaging teeth thereon cooper-- ating to form pumping chambers andsaid teeth having diametrically opposite full mesh and open meshpositions, the inner of said rotors being rotatable about an axis fixedwith respect to said housing, said outer rotor being bodily shii'tabieto' limit such shiitable movement thereof. said step surfaces beingdirectly engageable with said outer rotor and each serving as a bearingtherefor when in engagement therewith, said housing having an inlet portand an outlet port opening thereinto, and said surfaces being soconstructed and arranged as to maintain the pumping chambers opening upbetween said teeth moving awav I from said full mesh position andapproaching aid open mesh position in communication with said inletport, and the pumping chambers formed between said teeth moving awayfrom said open mesh position and approaching said full mesh position inopen communication-with said outlet port, regardless of the direction ofrotation of said rotors and the consequent corresponding shiitabieposition of said outer rotor.

EUGENE S. WITCHGER.

